Locals pay 1110 kina ($510) for "registration as a shareholder" in a carbon trading company with promises of big dividends from the millions expected from PNG's carbon trading.

A receipt is given, and that is the last time villagers see the agent and their money.

This scam is a thumbnail of the broader concerns plaguing PNG's efforts to best utilise their lucrative rainforests, the third largest in the world.

Dave Melick, of the PNG arm of the conservation group WWF, said confusion in the provinces was one concern, while credibility, corruption and carbon trading complexities were other hurdles PNG faced. "People in the bush are calling it 'money bilong sky' [sky money] or 'selling the air' or 'selling the gas above'.

"Some have asked WWF, 'Who pays for the transport costs?' when they cut their tree, burn the logs and bring the carbon to Port Moresby," Mr Melick said. "A lot of people think you sell the gas over the forest canopy and they're not quite sure how to capture it. There is real confusion.'

Problems associated with PNG's infamous logging industry translated into moves towards a carbon market, he said. "We're telling people not to sign anything as there is no policy or legislation."

This month Reuters news agency and the magazine The Economist reported a series of anomalies with PNG's Office of Climate Change. It appears the office has been offering millions of dollars worth of carbon credits while no legislation or policy exists in PNG or under UN guidelines.

Betha Somare, a spokeswoman for the Prime Minister, Michael Somare, said a review was being conducted into the "apparent irregularities".